CN103017890B - Introduced capacitive device for measuring horizontal ground micro-vibration - Google Patents

Abstract

The invention discloses an external capacitive measuring device for ground trace horizontal vibration, which consists of a standard signal generator (11), an external capacitive sensor (12), a negative feedback operational amplifier (13), a low-pass filter and a display system (14); the external capacitive sensor includes an external copper column (5) set on the ground, and a capacitive sheet (4) set on the top thereof, and a spacer is set on the periphery of the copper column at a radius of ^2m2 . Vibration ditch (8), steel column A (6) and steel column B (10) are set on the outside of the vibration isolation ditch, steel beams (7) are set on the top of the two steel columns, and measuring electrodes (1 ), the shielding electrode (2) and the shielding electrode shell (3), there is an excitation source (9) within the closed range of the vibration isolation ditch (8); the present invention is simple in structure, easy to use, and is convenient for horizontal vibration in two vertical directions at the same time It can be specially used to accurately test the trace horizontal vibration of the ground.

Description

A device for measuring ground micro-horizontal vibration by external capacitance

technical field

The invention relates to a horizontal vibration measuring device, in particular to an external capacitive displacement sensor and a vibration test, which is suitable for the measurement of ground trace vibrations.

Background technique

The discharge structure of high dams is prone to fatigue or vibration damage under the long-term discharge load, which seriously affects the normal operation and benefit of the project. Therefore, effective detection methods must be found to quickly and accurately discover hidden dangers and diseases in hydraulic structures, effectively predict their safety conditions, and evaluate their operational reliability. Therefore, how to obtain the vibration information of the structure accurately and conveniently is an important prerequisite for monitoring the operation status of hydraulic structures. The existing vibration testing means are to install displacement or acceleration sensors on the vibrating structure to obtain the vibration parameters of the structure. When some mass concrete vibrates slightly, the horizontal vibration cannot be measured by displacement or acceleration sensors.

There is a non-contact capacitive displacement sensor in the micro-displacement test of the structure. The general structure of this sensor includes two parts: the measuring electrode and the shielding protection electrode. There are also many principles, methods and instruments for displacement measurement. Such as: capacitance calculation method, capacitance resonance method, etc., the measured displacement is converted into electrical output through transformation. Take the capacitance algorithm measuring instrument as an example: the measurement principle of the instrument is to output the voltage of the capacitance algorithm Among them, V _b is the standard signal voltage of the instrument circuit; C _b is the standard capacitance in the instrument circuit. It can be seen from the formula that its voltage output is proportional to the measured displacement. The non-contact capacitive displacement sensor has many excellent characteristics and is widely used, but it is not suitable for the vibration test of large-volume objects.

Contents of the invention

The object of the present invention is to provide an external capacitive type that is easy to manufacture and can measure the micro-vibration of hydraulic structures conveniently and accurately, aiming at the problem that the micro-level vibration of large-volume concrete is difficult to accurately test in the dam safety monitoring. A device for measuring horizontal vibrations of the ground.

The present invention is realized through the following technical solutions.

An external capacitive measuring device for ground micro-horizontal vibration is composed of a standard signal generator 11, an external capacitive sensor 12, a negative feedback operational amplifier 13, a low-pass filter, and a display system 14; the external capacitive The sensor 12 includes a measuring electrode and a shielding electrode. It is characterized in that an external lead copper column 5 is arranged on the vibrating ground, and capacitor plates 4 are respectively arranged on two vertical surfaces perpendicular to each other on the top of the external lead copper column 5 , each serving as a capacitor. An electrode; a vibration isolation ditch 8 is provided at the periphery of the outer lead copper column 5, at a position of 2m ² , the depth is 1m, and the width is 0.2m; the symmetrical position of the outer side of the vibration isolation ditch 8 is provided with steel columns A6 and Steel column B10, steel beams 7 are arranged on the top of the two steel columns, measuring electrodes 1, shielding electrodes 2 and shielding electrode shells 3 are arranged under the steel beams 7; A pair of measuring electrodes 1 are arranged at the vertical positions at both ends, and the pair of measuring electrodes 1 corresponds to two capacitive sheets 4; an excitation source 9 is provided in the closed range of the vibration isolation ditch 8; The front end is connected with the standard signal generator 11, and the back end of the external capacitive sensor 12 is connected with a negative feedback operational amplifier 13, a low-pass filter and a display system 14 in sequence.

The vibration isolation groove 8 can also be closed in any shape.

The external copper column 5 is a cylinder with a height of 5 cm and a diameter of 0.5 cm.

The steel column A6 and the steel column B10 are cylinders with a height of 10 cm and a diameter of 1 cm.

The beneficial effect of the present invention is that it not only has the non-contact measurement error, friction thermal noise and heat loss of the existing capacitive non-contact displacement measurement method; it also has the advantages of fast measurement speed, good frequency response, high signal-to-noise ratio and The characteristics of low input energy. In addition, the present invention is simple in structure and easy to use, improves the shortcoming that ordinary capacitive displacement sensors can only test displacement in one direction, and can test vibrations in two mutually perpendicular directions on the horizontal plane at the same time, so it can be specially used for existing sensors that cannot accurately test Tiny horizontal vibrations on the ground.

Description of drawings

Fig. 1 is the front view of the external capacitive sensor of the present invention;

Fig. 2 is the top view of the external capacitive sensor of Fig. 1;

Fig. 3 is a structural block diagram of an external capacitive measuring device for ground trace horizontal vibration.

The reference signs of the present invention are as follows:

1——Measuring electrode 2——Shield electrode

3——shielding electrode shell 4——capacitor sheet

5——External copper column 6——Steel column A

7——Steel Beam 8——Vibration Isolation Ditch

9——Incentive source 10——Steel column B

11———standard signal generator 12———external capacitive sensor

13——Negative feedback operational amplifier 14——Low-pass filter and display system

Detailed ways

The invention makes full use of the characteristics of structural vibration. For a small-mass column fixed vertically on the ground, when the vibration frequency of the ground is much lower than the natural frequency of the column, the vibration of the column is completely consistent with the vibration of the ground. In addition, the test device of the present invention adopts a capacitive sensor, which can simultaneously test vibrations in two vertical directions on the horizontal plane.

The working principle of the external capacitive measurement device for measuring ground trace level vibration is that the voltage output The measured displacement is converted into a voltage output through transformation, and the voltage output is proportional to the measured displacement. The vibration of the copper column fixed vertically on the ground is exactly the same as the vibration of the ground. Therefore, the change of the passing voltage is proportional to the ground displacement, and the change of the ground displacement can be calculated by the output of the voltage.

As shown in FIG. 2 , the present invention consists of a standard signal generator 11 , an external capacitive sensor 12 , a negative feedback operational amplifier 13 , a low-pass filter and a display system 14 .

FIG. 1 is a schematic structural diagram of an external capacitive sensor of the present invention, and FIG. 2 is a top view of FIG. 1 . As can be seen from the figure, an external lead copper column 5 is arranged on the vibrating ground, and a capacitor sheet 4 is respectively arranged on two mutually perpendicular vertical surfaces at the top of the external lead copper column 5, each serving as an electrode of a capacitor; The periphery of the column, the position of square circle 2m ² is provided with vibration isolation ditch 8, vibration isolation ditch 8 is a closed circular structure, also can be closed arbitrary shape, its depth is 1m, and width is 0.2m; Said vibration isolation ditch A steel column A6 and a steel column B10 are arranged at the symmetrical position of the outer side of 8, which are cylinders with a height of 10 cm and a diameter of 1 cm; a steel beam 7 is arranged on the top of the two steel columns, and a measuring electrode 1, The shielding electrode 2 and the shielding electrode shell 3; the shielding electrode 2 is in a 90° double-fold shape, and a pair of measuring electrodes 1 are arranged at vertical positions at both ends of the shielding electrode shell 3, and the pair of measuring electrodes 1 correspond to two capacitor sheets 4; Also be provided with excitation source 9 in the closed range of vibration isolation ditch 8; The front end of described externally drawn capacitive sensor 12 is connected with standard signal generator 11, and the rear end of externally drawn capacitive sensor 12 is connected with negative feedback operational amplifier successively 13 and low pass filter and display system 14.

The use of the present invention will be described below by taking the sinusoidal vibration with an amplitude of 0.1 μm and a frequency of 1 Hz on the ground as an example.

Fix the external copper column 5 with a height of 5 cm and a diameter of 0.5 cm vertically on the ground. The natural vibration frequency of this copper column is very high, reaching more than tens of hertz, which is much higher than the vibration frequency of the ground. Therefore, at any time, the copper column The motion parameters (displacement, acceleration, etc.) of the ground are almost identical to those of the ground. So the vibration of the ground can be obtained by measuring the vibration of the copper pillar. When selecting copper pillars, it is necessary to choose copper pillars with high natural vibration frequency. The higher the natural vibration frequency of copper pillars, the higher the accuracy of copper pillars reflecting ground vibration. Capacitive plates are fixed on two vertical surfaces perpendicular to each other on the top of the external lead copper column, each serving as a pole of the capacitive sensor. The ground vibrates under the action of the excitation source 9, and there is a vibration isolation ditch 8 with a radius of 2m ² , a width of 0.2m, and a depth of 1m around the vibrating ground, which avoids the interference of the surrounding ground vibration on the ground vibration under the action of the excitation source. Steel beam 7 is supported by steel column A6 and steel column B10 erected outside vibration isolation ditch 8 , measuring electrode 1 and shielding electrode 2 of capacitive displacement sensor 12 are installed on steel beam 7 . The measuring electrode 1 and the capacitive sheet 4 fixed on the external copper column 5 form two pairs of electrodes of the capacitance respectively, forming a capacitive sensor. When the ground vibrates, the instrument switch is turned on, the vibration of the steel column causes the distance between the electrodes of the capacitive sensor to change, the signal generated by the standard signal generator 11 changes through the capacitive displacement sensor, and the changed signal passes through the negative feedback operational amplifier 13 and The low-pass filter 14 can then be displayed on the display system 14 .

Claims (3)

1. A device for externally leading capacitive measurement of ground trace horizontal vibrations, comprising a standard signal generator (11), an externally leading capacitive sensor (12), a negative feedback operational amplifier (13) and a low-pass filter and a display system ( 14) composition; described external lead capacitive sensor (12) comprises measuring electrode and shielding electrode, it is characterized in that, be provided with external lead copper post (5) on vibrating ground, at the external lead copper post (5) top two mutual The vertical vertical planes are respectively provided with capacitor plates (4), which are respectively used as an electrode of the capacitor; a vibration isolation ditch (8) is provided on the periphery of the external lead copper column (5), at a position of ^2m2 , and its depth is 1m. The width is 0.2m; a steel column A (6) and a steel column B (10) are arranged at symmetrical positions on the outside of the vibration isolation ditch (8), and a steel beam (7) is arranged on the top of the two steel columns. The measuring electrode (1), shielding electrode (2) and shielding electrode shell (3) are arranged below (7); the shielding electrode (2) is in the shape of 90° folded in half, and the vertical position of both ends of the shielding electrode shell (3) is provided with a For the measuring electrode (1), the pair of measuring electrodes (1) corresponds to the two capacitor sheets (4); an excitation source (9) is provided within the closed range of the vibration isolation ditch (8); the external capacitance The front end of the type sensor (12) is connected with the standard signal generator (11), and the rear end of the external capacitive sensor (12) is connected with a negative feedback operational amplifier (13) and a low-pass filter and a display system (14) successively; The vibration isolation groove (8) is closed in any shape. 2. according to the device of the external lead capacitive measurement ground trace horizontal vibration of claim 1, it is characterized in that, described external lead copper post (5) is the cylinder of height 5cm, diameter 0.5cm. 3. The device for measuring ground micro-horizontal vibrations by external capacitive measurement according to claim 1, characterized in that, said steel column A (6) and steel column B (10) are cylinders with a height of 10cm and a diameter of 1cm.